Transitional cell carcinoma of upper urinary tract vs. benign lesions: distinctive MSCT features

The transitional cell carcinoma (TCC) of the upper urinary tract is relatively uncommon. The clinical presentation of TCCs and many other diseases of the upper urinary tract are nonspecific, and most of these lesions are usually necessary to be evaluated by computed tomography (CT) urography. CT appearances of TCCs can be classified as papillary, infiltrating papillary, and diffusely infiltrating tumor. Most TCCs of the upper urinary tract can be identified on the bases of characteristic CT appearances. However, some benign lesions may mimic different categories of TCCs and should be taken into account for differentiating diagnosis. These lesions include endometriosis, nephrogenic adenoma, mycetomas, malacoplakia, and inflammatory pseudotumor which are similar to infiltrating papillary TCCs; complex urolithiasis, passed stone of ureter and ureteropelvic junction, chronic ureteropelvic junction obstruction with superimposed infection, atypical pyelonephritis, and tuberculosis which mimic diffusely infiltrating TCCs, and fibroepithelial polyp which has the same CT appearances as papillary TCCs. The useful CT signs to make differential diagnosis involve enhanced pattern, location of lesion, induration of urinary tract, and range of thickening of urinary wall. The three-dimension (3D) reconstructed images is useful in making differential diagnosis.